The present invention is concerned with producing a cavity in the surface of an organic plastic body. It is particularly concerned with producing such a cavity having an optical quality finish.
The invention arose in connection with providing a segment member in an organic plastic, ophthalmic, multifocal lens. More particularly, the lens was the organic plastic lens for a glass-plastic, laminated, multifocal lens blank. Accordingly, the invention is primarily described with reference to producing such an article, but its broader application will be readily apparent.
A three-layer, composite lens structure is disclosed in U.S. Pat. No. 4,793,703 (Fretz, Jr.); also in pending application Ser. No. 07/325,880, filed Mar. 20, 1989 in the name of E. R. Fretz, Jr. and assigned to the assignee of this application. This lens structure is composed of an inorganic glass layer, a layer of a rigid, organic plastic and an interlayer of a flexible, organic adhesive. These disclosures are primarily concerned with single vision lenses, that is, lenses that provide one type of visual correction.
A copending application, Ser. No. 07/682,479, filed Apr. 8, 1991 in the name of David Dasher et al., entitled HIGH INDEX, ORGANIC LENS MEMBER and assigned to the assignee of this application, is concerned with a multifocal lens structure. This is a four-component, glass-plastic, laminated structure exhibiting optical quality transmission. A characteristic feature of this lens structure is an organic plastic segment embedded in the front, convex surface of the major, organic plastic lens of the structure. The segment has a higher refractive index than the major element.